https://www.amazon.com/Climate-Wars-Fight-Survival-Overheats...
It will definitely change geopolitics for the foreseeable future.
The last scenario talks about, if I recall correctly, the oceans becoming more welcoming to bacteria that produce hydrogen sulfide. Sorry, I don't remember the details, but will update tonight from the book at home if I remember.
If you are looking for a fictional take, check out "The Water Knife" by Paolo Bacigalupi: https://www.amazon.com/Water-Knife-Paolo-Bacigalupi/dp/08041...